The present invention is directed to the transdermal administration of oxybutynin together with a suitable permeation enhancer. The invention includes a transdermal drug delivery device comprising a matrix adapted to be placed in oxybutynin- and permeation enhancer-transmitting relation with the skin site. The matrix contains sufficient amounts of a permeation enhancer and of oxybutynin, in combination, to continuously administer to the skin for a predetermined period of time the oxybutynin to provide an effective therapeutic result. The invention is also directed to a method for the transdermal administration of a therapeutically effective amount of oxybutynin together with a skin permeation-enhancing amount of a suitable permeation enhancer.